1. Field of the Invention
The present invention relates to a valve control means for an internal combustion engine and to an internal combustion engine.
2. Background Art
Modern combustion engines using spark ignition combustion processes afford potential for reducing the fuel consumption by way of a reduction of the gas exchange losses. To this end, dethrottling of the engine is an expedient way. There is already a multiplicity of systems for variable or fully variable valve control on the market.
DE 101 40 635 A1 discloses a valve train apparatus for the independent variable lift adjustment of the gas exchange valves of an internal combustion engine, in which valve train apparatus the gas exchange valves are actuated by way of additional rocker arms which are positioned by way of independent adjusting bars and are moved by way of a camshaft in a slotted guide track which is fixed to the machine. Here, a rocker arm rolls in the slotted guide track by way of a mounted roller and at the same time rolls along the contour of an adjusting bar on a second roller which is mounted in the lever. Opposite the slotted guide roller, the rocker arm has a work curve which runs on the roller of a roller drag lever which is preferably mounted on a hydraulically actuated play compensation element. In order to set a valve lift, the adjusting bar is positioned or regulated in a guide in accordance with a torque request. In DE 101 40 635 A1, in particular, the roller drag lever is driven by way of a further rocker arm which, during a rotation of the camshaft, is moved by way of a roller along a trajectory which is defined by a slotted guide which is fixed to the housing.
U.S. Pat. No. 1,099,264 discloses a valve control means for high speed internal combustion engines, in which valve control means the opening movement of a valve is achieved by way of a drag lever which interacts with a cam and the closing movement takes place by way of double-armed levers which act on the valve and interact with cam disks, the cam disks being arranged coaxially with respect to the cam in a manner known per se, and the double-armed levers being mounted on both sides of the drag lever substantially coaxially with respect to said drag lever and with respect to one another. Positive guidance of the valve takes place by way of said valve control means. All the levers are mounted on a common axis. The levers are not coupled to one another.
The fully variable systems which are in use are all very complicated. Furthermore, the systems tend to be heavy as a result of the multiplicity of components and require a corresponding design of the valve springs with high spring forces. This usually leads to high frictional losses.